Chromosomal diversification and karyotype evolution of diploids in the cytologically diverse genus Prospero (Hyacinthaceae)

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Next-generation sequencing reveals the impact of repetitive DNA in phylogenetically closely related genomes of Orobanchaceae

We used next-generation sequencing to characterize the genomes of nine species of Orobanchaceae of known phylogenetic relationships, different life forms, and including a polyploid species. The study species are the autotrophic, nonparasitic Lindenbergia philippensis, the hemiparasitic Schwalbea americana, and seven nonphotosynthetic parasitic species of Orobanche (Orobanche crenata, Orobanche cumana, Orobanche gracilis (tetraploid), and Orobanche pancicii) and Phelipanche (Phelipanche lavandulacea, Phelipanche purpurea, and Phelipanche ramosa). Ty3/Gypsy elements comprise 1.93%–28.34% of the nine genomes and Ty1/Copia elements comprise 8.09%–22.83%. When compared with L. philippensis and S. americana, the nonphotosynthetic species contain higher proportions of repetitive DNA sequences, perhaps reflecting relaxed selection on genome size in parasitic organisms. Among the parasitic species, those in the genus Orobanche have smaller genomes but higher proportions of repetitive DNA than those in Phelipanche, mostly due to a diversification of repeats and an accumulation of Ty3/ Gypsy elements. Genome downsizing in the tetraploid O. gracilis probably led to sequence loss across most repeat types

Introgression of apomixis into sexual species is inhibited by mentor effects and ploidy barriers in the Ranunculus auricomus complex

Background and Aims Apomictic plants maintain functional pollen, and via pollination the genetic factors controlling apomixis can be potentially transferred to congeneric sexual populations. In contrast, the sexual individuals do not fertilize apomictic plants which produce seeds without fertilization of the egg cells. This unidirectional introgressive hybridization is expected finally to replace sexuality by apomixis and is thought to be a causal factor for the wide geographical distribution of apomictic complexes. Nevertheless, this process may be inhibited by induced selfing (mentor effects) of otherwise self-incompatible sexual individuals. Here whether mentor effects or actual cross-fertilization takes place between diploid sexual and polyploid apomictic cytotypes in the Ranunculus auricomus complex was tested via experimental crosses. ¿ Methods Diploid sexual mother plants were pollinated with tetra- and hexaploid apomictic pollen donators by hand, and the amount of well-developed seed compared with aborted seed was evaluated. The reproductive pathways were assessed in the well-developed seed via flow cytometric seed screen (FCSS). ¿ Key Results The majority of seed was aborted; the well-developed seeds have resulted from both mentor effects and cross-fertilization at very low frequencies (1.3 and 1.6% of achenes, respectively). Pollination by 4x apomictic pollen plants results more frequently in cross-fertilization, whereas pollen from 6x plants more frequently induced mentor effects. ¿Conclusions It is concluded that introgression of apomixis into sexual populations is limited by ploidy barriers in the R. auricomus complex, and to a minor extent by mentor effects. In mixed populations, sexuality cannot be replaced by apomixis because the higher fertility of sexual populations still compensates the low frequencies of potential introgression of apomixi

Sphagnum incundum a new species in Sphagnum subg. Acutifolia (Sphagnaceae) from boreal and arctic regions of North America

We describe Sphagnum incundum in Sphagnum subg. Acutifolia (Sphagnaceae, Bryophyta). We used both molecular and morphological methods to describe the new species. Molecular relationships with closely related species were explored based on microsatellites and nuclear and plastid DNA sequences. The morphological description is based on qualitative examination of morphological characters and measurements of leaves and hyalocysts. Morphological characters are compared between closely related species. The results from Feulgen densitometry and microsatellite analysis show that S. incundum is gametophytically haploid. Molecular analyses show that it is a close relative to S. flavicomans, S. subfulvum and S. subnitens, but differs both genetically and in morphological key characters, justifying the description of S. incundum as a new species. The new peatmoss is found in North America along the western coast of Greenland, in Canada from Quebec and Northwest Territories, and Alaska (United States). The new species has a boreal to arctic distribution.publishedVersio

Data from: Interploidal hybridization and mating patterns in the Sphagnum subsecundum complex

Polyploidization is thought to result in instant sympatric speciation, but several cases of hybrid zones between one of the parental species and its polyploid derivative have been documented. Previous work showed that diploid Sphagnum lescurii is an allopolyploid derived from the haploids S. lescurii (maternal progenitor) and S. subsecundum (paternal progenitor). Here we report the results from analyses of a population where allodiploid and haploid S. lescurii co-occur and produce sporophytes. We tested (1) whether haploids and diploids form hybrid triploid sporophytes, (2) how hybrid and non-hybrid sporophytes compare in fitness, (3) whether hybrid sporophytes form viable spores, (4) the ploidy of any viable gametophyte offspring from hybrid sporophytes, (5) the relative viability of sporelings derived from hybrid and non-hybrid sporophytes, and (6) if interploidal hybridization results in introgression between the allopolyploid and its haploid progenitor. We found that triploid hybrid sporophytes do occur and are larger than non-hybrid sporophytes, but exhibit very low germination percentages and produce sporelings that develop more slowly than those from non-hybrid sporophytes. All sporophytes attached to haploid gametophytes were triploid and were sired by diploid males, but all sporophytes attached to diploid gametophytes were tetraploid. This asymmetric pattern of interploidal hybridization is related to an absence of haploid male gametophytes in the population. Surprisingly, all sporelings from triploid sporophytes were triploid, yet were genetically variable, suggesting some form of aberrant meiosis that warrants further study. There was limited (but some) evidence of introgression between allodiploid and haploid S. lescurii

Sphagnum incundum a new species in Sphagnum subg. Acutifolia (Sphagnaceae) from boreal and arctic regions of North America

We describe Sphagnum incundum in Sphagnum subg. Acutifolia (Sphagnaceae, Bryophyta). We used both molecular and morphological methods to describe the new species. Molecular relationships with closely related species were explored based on microsatellites and nuclear and plastid DNA sequences. The morphological description is based on qualitative examination of morphological characters and measurements of leaves and hyalocysts. Morphological characters are compared between closely related species. The results from Feulgen densitometry and microsatellite analysis show that S. incundum is gametophytically haploid. Molecular analyses show that it is a close relative to S. flavicomans, S. subfulvum and S. subnitens, but differs both genetically and in morphological key characters, justifying the description of S. incundum as a new species. The new peatmoss is found in North America along the western coast of Greenland, in Canada from Quebec and Northwest Territories, and Alaska (United States). The new species has a boreal to arctic distribution

Germination Experience Microsatellite Data

Mothers, sporophytes and lab reared sporelings microsatellite data. Genome size of some samples was measured by flow cytometry. Haploid samples coded as haploid. Incomplete heterozygous diploid, triploid and tetraploid samples are coded accordingly to their microsatellite phenotype

Gametophytes_MsatData

Microsatellite data for gametophytes - mother, sterile and male plants. Haploids coded as homozygous diploids

Sporophytes_MsatData

Microsatellite data for triploid and tetraploid sporophytes